BIOTECH: New stem cell on the block

Potential advantage in disease treatment

All the various kinds of stem cells being researched for
treating diseases and injuries ---- embryonic, adult, cord blood
---- have their limitations. So a team of scientists has created a
new stem cell.

Called induced conditional self-renewing progenitor, or ICSP,
cells, these are ordinary cells given just enough "stemness" (the
ability to self-renew) to make more of their kind. Then they can be
transplanted into an animal, mature, and then fix the problem.

Rats with brain injuries mimicking a hemorrhagic stroke improved
after receiving the ICSP cells, according to a study by a research
team including Evan Snyder of the Sanford Burnham Medical Research
Institute.

The team published their findings earlier this month in the
Proceedings of the National Academy of Sciences.

Snyder said the ICSP cells could prove more useful for therapy
than embryonic stem cells, derived from days-old embryos, or cells
made to act like them, called induced pluripotent stem (IPS)
cells.

The latter two kinds of cells undergo great transformations
before becoming the target cells meant for therapy, Snyder said.
Embryonic stem cells have a disturbing tendency to form tumors. IPS
cells, made from normal cells such as skin cells, contain DNA
"reprogramming" errors that could make the cells dangerous in
humans.

The ICSP cells undergo a less radical transformation, so there's
less chance for errors to creep in, Snyder said.

The cells were made by using a virus to insert a gene called
v-Myc into neural "progenitor" cells. Progenitor cells can divide
only a few times before becoming the target cell. The v-Myc gene
keeps cell proliferation going.

Researchers used a kind of gene that only works in the presence
of the antibiotic tetracycline, which was supplied in the
laboratory culture. When the cells were transplanted into the rat
brains, they differentiated into functioning neurons.